Methods of the prior art provide extraction of the acid gases. (H2S and CO2) by means of a treatment using a solvent containing amines, for example methyldiethanolamine (MDEA), which has a very high affinity with H2S.
The amines used by natural gas treating methods are in aqueous solution notably to modify the chemical equilibria, to reduce vapour losses, to reduce the regeneration temperature at atmospheric pressure and to limit co-absorption of hydrocarbons. The fact that the amines are in aqueous solution does not allow dehydration of the gas to be treated and has the drawback of moistening a gas which would be intrinsically dry or which would have already been dehydrated. In general, after deacidizing with a method using an amine solvent, the natural gas has to be dehydrated by means of an additional treatment using a glycol-based solvent. The necessity of using an additional treatment to dehydrate a natural gas deacidized by a method using a solvent containing amines is expensive and requires an additional infrastructure.
The present invention provides a deacidizing and dehydration method using an amine-containing solvent and avoiding the drawbacks of the prior art.